Radiation therapy is a common curative procedure to treat cancer. The goal of the radiotherapy process is to expose the tumor to a sufficient dose of radiation so as to eradicate all cancer cells. The radiation dose is often close to the tolerance level of the normal body tissues. Therefore, it is necessary to determine the dosage levels in different parts of the irradiated body with high accuracy. Intensity Modulated Radiation Therapy (IMRT) is a complex radiation delivery system, with there being many steps between the calibration of the beam of the therapy radiation unit to the determination of the radiation dose at the desired point of interest in the patient. IMRT typically uses a linear accelerator (“LINAC”) as the source of the radiation beam used to treat the tumor. The linear accelerator typically has a radiation beam source that is rotated about the patient and directs the radiation beam toward the tumor to be treated.
In radiation therapy, it is important to ensure that the absolute dose delivered is consistent with the planned dose, and that the critical spatial resolution of that dose is consistent with the planned dose distribution. The verification of IMRT patient treatment includes the use of dosimeters to measure the radiation dosage during the treatment (generally referred to as “in-vivo dosimetry”).
With respect to the design of such dosimeters, it is known in the art to use diodes to measure radiation doses to patients and to output radiation measurements to a computer for further processing. One such device, sold under the trademark IVD by Sun Nuclear Corporation, has a detection pod which requires the user to select from a plurality of different possible radiation detectors (at least four different sets), with the selected set being removably coupled to the detection pod. The radiation detectors selected depends upon the particular patient tests to be undertaken, with each different radiation detector selected requiring recalibration. In addition to the added complexity caused by having calibrate different detectors each time they are changed, the need for the user to have available so many different types of detectors is quite expensive. Moreover, the selection process between so many possible radiation detectors may lead to errors being made by the user not selecting the right radiation detector.
Additionally, the Sun Nuclear unit provides the option to send processed data from the detection pod to a computer or control module. However, in this Sun Nuclear product, the data is mostly processed within the detection pod and the computer or control unit, depending upon the option selected, is therefore little more than an alternative display device. Hence, in the Sun Nuclear unit the greater processing power of the PC is not used to convert the raw count to a radiation measurement.
What is needed is a portable dosimeter that can use the same radiation detectors without the need for continuous recalculations for different radiation detectors. Additionally, it is desirable to maximize processing of data in the computer.